Plenum tube



FIG. 1 is a first perspective view of a plenum tube, showing my new design;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a third perspective view thereof;

FIG. 4 is a fourth perspective view thereof;

FIG. 5 is a fifth perspective view thereof;

FIG. 6 is a sixth perspective view thereof;

FIG. 7 is a top view thereof;

FIG. 8 is a bottom view thereof;

FIG. 9 is a front view thereof; and

FIG. 10 is a rear view thereof;

FIG. 11 is a left view thereof; and,

FIG. 12 is a right view thereof. 

CLAIM The ornamental design for a plenum tube, as shown and described. 